Note 9 - Marketable Securities (Tables)

9 Months Ended

Sep. 30, 2019

Notes Tables

Debt Securities, Held-to-maturity [Table Text Block]

(in thousands)	September 30, 2019		December 31, 2018		September 30, 2018
U.S. Government and agency obligations	$	37,918	$	24,996	$	30,000
Corporate bonds		—		5,006		5,010
Total short-term marketable securities		37,918		30,002		35,010
U.S. Government and agency obligations		10,000		36,098		46,093
Total long-term marketable securities		10,000		36,098		46,093
Total marketable securities	$	47,918	$	66,100	$	81,103

Debt Securities, Held-to-maturity, Fiscal Year Maturity [Table Text Block]

(in thousands)	September 30, 2019
Due within one year	$	37,918
Due in one to five years		10,000
Total	$	47,918